We study the effect of a high magnetic field (B) on the current–voltage characteristics, I(V), of a GaAs/(AlGa)As resonant tunneling diode incorporating a layer of ring-shaped quantum dots (QDs) in the quantum well (QW). The dots give rise to a series of four unusual resonances in I(V) which show a high degree of reproducibility across the epitaxial wafer. By combining data for B parallel and perpendicular to the growth axis z, we identify that the unusual resonances arise from resonant tunneling into QD excited states with 2pz-like symmetry. The two series of magneto-oscillations in I for Bz allow us to determine the resonant charging and discharging of the QW with varying bias.

4 páginas, 3 figuras.-- PACS: 73.23. b; 73.63.Kv; 73.40.Gk.-- Proceedings of the 12th International Conference on Modulated Semiconductor Structures (ICPS-12).

We thank EPSRC (UK), MCYT (Spain), SANDiE (NMP4-CT-2004-500101) and the EU (RII3-CT-2004- 506239).

Peer reviewed